Modular planar array antenna architectures, such as those intended for spaceborne and airborne applications, are typically comprised of a plurality of mutually adjoining relatively thin, tile or brick-configured, solid metallic (e.g., quarter inch thick aluminum) plates, an individual one of which is diagrammatically shown at 10 in FIG. 1 and a joined-together array of which is shown in plan in FIG. 2. As shown in FIG. 1, a respective plate 10 includes an outer or front surface 11 upon which a plurality of antenna elements 14 are mounted. Signal processing and beam forming circuitry 15 is distributed over and mounted to a rear surface 12 of the plate 10, and is coupled to the antenna elements 14 on the plate's front surface by means of feed-through sections of RF transmission line 13, which pass through bores 16 in the plate 10, proper.
One of the major drawbacks to this solid plate-configured architecture is the substantial weight penalty of using solid metal plate to provide the requisite stiffness and strength. Solid aluminum plate, for example, has a weight density on the order of 170 lb./ft.sup.3. In addition, a substantial amount of rear plate surface real estate and an associated complex component layout are required to support the RF signal processing (amplifier and impedance/phase control) and distribution (beam-forming) circuitry components 15. Further, the need to provide respective impedance-matching transmission line feed elements through bores in the plate 10 for coupling the circuitry components 15 on the rear surface 12 to the antenna elements 14 on the front surface 11 increases the complexity of the overall layout and tile assembly.